97 E300D - OBD says EGR problem, no CEL or codes - PeachParts Mercedes-Benz Forum

rmasteller · #1 07-03-2019, 03:48 PM

Hi. I replaced a broken vacuum line in my engine bay (short line from intake manifold to MAP sensor) last night. On my way home from work today, CEL went away. Yea! So, I figured I'd put my cheap little OBD scanner on and see what it said.

- p0120, p0400
-CEL off
- Indicators
- Inc (Comp, EGR)

Cleared codes, retested:

- No codes
- CEL off
- Indicators
- Inc (EGR)

It did this while ignition on, but engine off.
It did this while driving and rescanning.

What kind of problem would an EGR system have that shows up on an OBD scanner (Actron CP9125) but doesn't throw a code?

Thanks!

rmasteller · #2 07-03-2019, 04:35 PM

Humorous thing - Looking for my own answers, i found this thread.
1997 E300 CODES P0400/P0120

The OP is Rod, I am Rodd. We both have 97 E300D's. He was fighting p0120, p0400 codes and fixed them by replacing the vac line from intake manifold to MAP sensor (among others). Even though my CEL was out, the first time I read the OBD codes today I had to clear p0120, p0400. This was after changing that same vac line to MAP sensor. Amazing how well our forum can work when searched properly.

Doesn't fix my current issue, just thought this was interesting/funny.

rmasteller · #3 07-03-2019, 04:40 PM

My OBD scanner manual is attached.

rmasteller · #4 07-03-2019, 05:10 PM

It's not for my OBD tool, but this site gives a nice explanation of ready indicators and drive cycles. I may not have an EGR issue, the reader was simply stating that the test is incomplete.

https://www.obdautodoctor.com/scantool-garage/obd-readiness-monitors-explained

'm much less worried now, but will use the code reader a few more times this week to ensure no codes return.

dieseldiehard · #5 07-04-2019, 07:47 PM

THANKS a lot for the link!!I
I am having issues with getting past the drive cycle to be able to allow the Smog system to visually inspect my '99 E300D.
tester said it showed an egr count cycle issue. Make that on two occasions, having driven several hundred miles between tests.
I've not had any CL lights alto I did have a bulb out and saw a Lamp Failure warning and fixed that.
I had driven almost 500 miles, mixed city and hwy (mostly highway) and it still said no-go

so I had an idea to reset the OBD. thats done now I am going to plan another driving exercise to see if it will satisfy the Smog police.
this is very frustrating! I wish I could hack that damn OBD II

DDH

rmasteller · #6 07-08-2019, 05:08 PM

It appears you have to perform very specific driving activities to count as a drive cycle for a specific test. Apparently this is sometimes done on dyno equipment. If you fail, maybe they can print out the required actions to complete the drive cycles for your test.

tjts1 · #7 07-08-2019, 05:24 PM

Quote:

Originally Posted by dieseldiehard

THANKS a lot for the link!!I
I am having issues with getting past the drive cycle to be able to allow the Smog system to visually inspect my '99 E300D.
tester said it showed an egr count cycle issue. Make that on two occasions, having driven several hundred miles between tests.
I've not had any CL lights alto I did have a bulb out and saw a Lamp Failure warning and fixed that.
I had driven almost 500 miles, mixed city and hwy (mostly highway) and it still said no-go

so I had an idea to reset the OBD. thats done now I am going to plan another driving exercise to see if it will satisfy the Smog police.
this is very frustrating! I wish I could hack that damn OBD II

DDH

It's a completely different system from the OP's 97. 97 was the last year that doesn't need smog check.